Simplify the following expression: $k = \dfrac{6ba - 4ca}{ca - 4a^2} - \dfrac{6ba}{ca - 4a^2}$ You can assume $a,b,c \neq 0$.
Solution: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{6ba - 4ca - (6ba)}{ca - 4a^2}$ $k = \dfrac{-4ca}{ca - 4a^2}$ The numerator and denominator have a common factor of $a$, so we can simplify $k = \dfrac{-4c}{c - 4a}$